My theory
From what I feel about it (and I mean feel in a psychic sense) there were 2 killers. They worked together, one was upper class and the other was like his errand boy but he was dirty and disgusting. They had a relationship, a sexual hangup for each other and women disgusted them but the slaughtering was exciting.
The dirty one was not as educated as the first and he did most of the work. They worked as a team, and one of them dressed as a woman so they could hide the bloody items beneath the skirts and no one would notice. A couple in an alley making out would seem normal so they used that ruse.
At times they pretended to be drunks walking around and the police were looking for a single man, not a pair. They easily got away because they were the opposite of what was expected...they were loud and obnoxious...the police walked right past them.
It was a sexual blood lust that wasn't satisfied by what they did, it became an obsession that couldn't be controlled until one of them killed the other.
The educated guy had a high-up position, I don't know if he was a lawyer or doctor but he pretended that he didn't know the dirty guy. They met in secret, the 1st guy lived away from the nasty place they hunted in.
Ok...my theory may seem a bit out there but when I get these feelings I go with them. I am seldom wrong and my husband is freaked out when I start any sentence with "I have a feeling".
Any thoughts???